wifi: cfg80211: Add KHZ_PER_GHZ to units.h and reuse

The KHZ_PER_GHZ might be used by others (with the name aligned
with similar constants). Define it in units.h and convert
wireless to use it.

Signed-off-by: Andy Shevchenko <[e-mail]>
Reviewed-by: Simon Horman <[e-mail]>
Link: https://msgid.link/[e-mail]
Signed-off-by: Johannes Berg <[e-mail]>

include/linux/units.h

···
 #define NANOHZ_PER_HZ		1000000000UL
 #define MICROHZ_PER_HZ		1000000UL
 #define MILLIHZ_PER_HZ		1000UL
+
 #define HZ_PER_KHZ		1000UL
-#define KHZ_PER_MHZ		1000UL
 #define HZ_PER_MHZ		1000000UL
+
+#define KHZ_PER_MHZ		1000UL
+#define KHZ_PER_GHZ		1000000UL
 
 #define MILLIWATT_PER_WATT	1000UL
 #define MICROWATT_PER_MILLIWATT	1000UL

net/wireless/reg.c

···
 #include <linux/verification.h>
 #include <linux/moduleparam.h>
 #include <linux/firmware.h>
+#include <linux/units.h>
+
 #include <net/cfg80211.h>
 #include "core.h"
 #include "reg.h"
···
 static bool freq_in_rule_band(const struct ieee80211_freq_range *freq_range,
 			      u32 freq_khz)
 {
-#define ONE_GHZ_IN_KHZ	1000000
 	/*
 	 * From 802.11ad: directional multi-gigabit (DMG):
 	 * Pertaining to operation in a frequency band containing a channel
 	 * with the Channel starting frequency above 45 GHz.
 	 */
-	u32 limit = freq_khz > 45 * ONE_GHZ_IN_KHZ ?
-			20 * ONE_GHZ_IN_KHZ : 2 * ONE_GHZ_IN_KHZ;
+	u32 limit = freq_khz > 45 * KHZ_PER_GHZ ? 20 * KHZ_PER_GHZ : 2 * KHZ_PER_GHZ;
 	if (abs(freq_khz - freq_range->start_freq_khz) <= limit)
 		return true;
 	if (abs(freq_khz - freq_range->end_freq_khz) <= limit)
 		return true;
 	return false;
-#undef ONE_GHZ_IN_KHZ
 }
 
 /*